For the phone book scene, a prop phone book was made out of foam and rubber, so that Keanu Reeves could genuinely smack Grill, played by The Game, with it. Although The Game insisted on Keanu using a real phone book, after one take in which he was hit with it, they switched back to the foam and rubber prop, because the real one really hurt The Game.
Detective Tom Ludlow (Keanu Reeves) wakes up at the beginning to the same alarm sound as in The Matrix (1999), where he played Thomas Anderson a.k.a. Neo.
The first of two movies where Keanu Reeves and Common play enemies who are trying to kill each other, the second one being John Wick: Chapter 2 (2017).
The film was shot in a grueling 43 days with very long hours for the cast and crew, according to director David Ayer.